Adaptive behavior must be timed appropriately. The goal of this research is to understand the cognitive and neural mechanisms that underlie this ability. The specific aim of this project is to study mechanisms whereby the dopamine system affects temporal information processing. In preliminary work, we replicated the well-documented immediate, unconditioned suppression of responding by the dopamine antagonist pimozide. However, we discovered that after several doses of pimozide, a conditioned response may develop to stimuli associated with drug administration. The conditioned response produces a change in temporal information processing. This grant is designed to explore how this conditioned response arises and how it influences information processing. The dopamine system has been implicated in psychiatric disorders such as schizophrenia and, perhaps, depression. By understanding the role of the dopamine system in cognition and by understanding the contributions of conditioning to the effectiveness of drugs, treatments can be developed that are of more rapid onset and greater effectiveness. Additionally, this work will contribute to understanding the operation and treatment of addictions. The rewarding properties of some addictive drugs appear to be mediated by the dopamine reward system. An understanding of how dopamine affects cognition can provide new understanding of drug effects. Furthermore, cues associated with drug-taking are important modulators of drug tolerance, craving and relapse. Consequently, a better understanding of conditioning processes that accompany drug taking can also lead to more effective interventions.